A superecliptic pHluorin (SpH) with a human prolactin hormone signal sequence was introduced to exon 2 of the mouse Drd2 gene, enabling the expression of a fused GFP-D2R protein. A loxP-flanked PGK-neomycin cassette was placed in intron 2. Cre-mediated recombination removed the floxed neo cassette. (J:286658)